1. Field of the Invention
The present invention relates to an apparatus and method for implantation of an in vivo sensor, and particularly to a minimally invasive method for implanting a sensor.
2. Description of the Prior Art
Certain sensors, such as glucose sensors, are intended for use in vivo, requiring that the sensors be implanted in a fashion consistent with their use. However, it is also desirable that the method of implantation be quick, easy and convenient. The method of implantation is advantageously one which is readily performed both by medical personnel administering to a patient, and also by the person being monitored. Since this person likely will not have medical training, the method should be one which can be performed reliably, such that the readings from the sensor are accurate.
The present invention provides a method which is readily performed for the implantation of a glucose or other sensor, and which uses an apparatus which provides quick and reliable results. While devices have existed for introducing a catheter into small vessels subcutaneously, the introduction of in vivo sensors in this manner has not been suggested.
In U.S. Pat. No. 4,417,886, issued to Frankhouser et al. on Nov. 29, 1983, there is disclosed a catheter introduction set. The Frankhouser patent describes an assembly including a catheter mounted on an introducer needle, with the tip of the needle extending slightly beyond the end of the catheter. A wire guide is received within the needle and attached to a guide tube extending rearwardly from the needle. In use, the needle is inserted into the lumen of the vessel, the spring wire guide is advanced into the vessel, and the catheter is then advanced forwardly to track the spring wire guide into the vessel to the desired position. Thereafter, the spring wire guide and needle are removed.
A comparable device, but without the wire guide, is currently marketed by MiniMed Technologies of Sylmar, Calif. under the name SOF-SET. This device includes a 24 gauge needle received within a short 24 gauge catheter. The needle includes a handle, and is used to introduce the catheter into the body by piercing through the skin. The catheter extends from a support adapted to be secured to the skin. A length of tubing also extends from the support, and communicates with the catheter upon withdrawal of the needle.
Methods and assemblies for the introduction of dual lumen catheters have also been identified. Dual lumen catheters have been noted as providing two means for access to a vessel, such as for withdrawal of blood samples and the infusion of drugs. An introducing needle assembly similar to that described in the Frankhouser patent, but including a double lumen needle, is disclosed in U.S. Pat. No. 4,935,008, issued to Lewis on Jun. 19, 1990. Similarly, the TWIN CATH.RTM. product from Arrow International, Inc., comprises an introducer including a two lumen catheter. One lumen of the catheter is round and receives a needle therein, and the other lumen has a C-shaped cross section and surrounds a portion of the round lumen.